1. Field of the Invention
The present invention relates to standoffs for substrates such as printed circuit boards. More specifically, the present invention relates to standoffs that can be used to unmate substrates.
2. Description of the Related Art
One known method for mating two substrates together is to use pairs of board-to-board connectors. FIG. 24 shows a first substrate 1050 with eight male connectors 1030, and FIG. 25 shows a second substrate 1060 with eight corresponding female connectors 1040. FIGS. 26 and 27 show the first and second substrates 1050 and 1060 connected to together. FIG. 27 also includes a partial cross-section of a male connector 1030 and a female connector 1040, showing that the contacts 1031 of the male connector 1030 and the contacts 1041 of the female connector 1040 are aligned along a centerline C.
However, mating and unmating the first and second substrates 1050 and 1060 from each other can cause problems, including damaging the plastic connector bodies of the male and female connectors 1030 and 1040, damaging the contacts 1031 and 1041 of the male and female connectors 1030 and 1040, fracturing solder joints, damaging the first and second substrates 1050 and 1060, injuring the hands of the person attempting to unmate the first and second substrates 1050 and 1060, and cracking traces included in or on the first and second substrates 1050 and 1060 by overstressing or over bending the first and second substrates 1050 and 1060 while unmating the male and female connectors 1030 and 1040. Further, during mating and unmating of the first and second substrates 1050 and 1060 from each other, plastic may be shaved off from the inner walls of the connector bodies of the male and female connectors 1030 and 1040, which can then move into critical contact areas. For example, during subsequent matings, the plastic shavings can become lodged between the contacts 1031 and 1041 of the connectors 1030 and 1040, thereby preventing an electrical connection between the first and second substrates 1050 and 1060.
Zipper mating and unmating methods have typically been used to mate and unmate substrates. The zipper mating method involves applying pressure to one side of one or both of the substrates, which causes the substrates to be angled, and not parallel, with respect to each other. The zipper unmating method, applied to the first and second substrates 1050 and 1060, is shown in FIG. 28. As shown in FIG. 28, the right side of the first substrate 1050 is lifted from the second substrate 1060, such that the male connectors 1030 begin to unevenly disengage from the female connectors 1040. Various tools, such as a screwdriver or a user's fingers, have typically been used to pry the substrates 1050 and 1060 apart. Custom unmating tools have also been used to unmate substrates, although such custom tools generally require large keepout areas on the substrates, reducing the area on the substrates for electrical traces and connectors. Pneumatic presses, which require additional cost and inconvenience, have also been used to unmate substrates. However, custom tools or pneumatic presses may still result in uneven unmating of the substrates 1050 and 1060.
Unmating the male connectors 1030 and the female connectors 1040 at an angle as shown in FIG. 28 can result in damage to the substrates 1050 and 1060 and the electrical connectors 1030 and 1040. For example, as shown in FIG. 29, repeated zipper mating and unmating can result in the contacts 1041 of the female connector 1040 deforming and not aligning with the corresponding contacts 1031 of the male connector 1030 along the centerline C, which can cause stubbing or mis-mating. For example, the contacts 1041 of the female connector 1040 can be deformed so that they are offset from the corresponding contacts 1031 of the male connector 1030, and thus causing the contacts 1041 of the female connector 1040 to mate with the incorrect contacts 1031 of the male connector 1030.
It has also been known to use standoffs or substrate spacers between mated substrates. However, when standoffs or substrate spacers are not used, incorrect board-to-board distances between the substrates can result, which can lead to insufficient contact wipe for corresponding connectors mounted on the substrates. Contact wipe is defined as the distance a contact rubs against the surface of its corresponding mating contact during mating and unmating. Insufficient contact wipe can lead to a poor electrical connection. For example, as shown in FIG. 26, the lack of any spacers between the substrates 1050 and 1060 can result in an insufficient contact wipe between the contacts 1031 of the male connector 1030 and the contacts 1041 of the female connector 1040.
Moreover, failure to use standoffs or substrate spacers can lead to additional problems, such as fretting corrosion in the contact area and fractured solder joints when the mated substrates 1050 and 1060 are exposed to vibrations or harsh environments.